FISHERY BULLETIN: VOL. 78, NO. 1 



25.0'7r SL; vomer with 0-12 teeth; pharyngobran- 

 chials II and III heavily toothed. 



Color in preservative dark brown to black over 

 entire surface of body (except for distal portion of 

 escal bulb) and oral cavity; all fins colorless in 

 specimens less than about 40 mm SL (except for 

 caudal rays in adolescent M. murrayi, Bertelsen 

 1951, fig. 161). 



Pectoral fin rays 15-23 (Table 2); pelvic fins ab- 

 sent. 



The following measurements, in percent of 

 standard length, are summarized for females (20- 

 120 mm SL) of all species: head depth 42.5-82.0; 

 least outside width between frontals 9.1-28.6; 

 head width 22.6-45.0; premaxillary length 36.3- 

 76.0; lower jaw length 36.7-78.0; width of pectoral 

 fin lobe 6.1-17.8; escal bulb width 1.9-11.3 



For description of males see Diagnosis above 

 and Bertelsen (1951). 



Genus Melanocetus Giinther 1864 



Females 



Melanocetus Giinther 1864:301-302, pi. 25 (type 

 species Melanocetus johnsoni Giinther 1864, by 

 monotypy). 



Melanocetus (subgenus Liocetus) Giinther 

 1887:56, pi. 11, fig. A (type species Melanocetus 

 murrayi Giinther 1887, by monotypy). 



Liocetus Goode and Bean 1896: 495-496, fig. 407 

 (type species Melanocetus murrayi Giinther 

 1887, by monotypy). 



Melanocoetus Smith 1949:429 (erroneous spelling 

 of Melanocetus, therefore taking the same type 

 species, Melanocetus johnsoni Giinther 1864). 



Linocetus Bertelsen 1951:40, 44 (erroneous spell- 

 ing of Liocetus, therefore taking the same type 

 species, Melanocetus murrayi Giinther 1887). 



Males 



Rhynchoceratias Parr 1927:30-33, fig. 11-12 (in 

 part; type species Rhynchoceratias brevirostris 

 Regan 1925, by subsequent designation of 

 Fowler 1936). 



Centrocetus Regan and Trewavas 1932:53, fig. 79 

 (type species Centrocetus spinulosus Regan and 

 Trewavas 1932, by monotypy). 



Xenoceratias Regan and Trewavas 1932:54-57, fig. 

 80-84 (type species Xenoceratias longirostris 

 Regan and Trewavas 1932, by subsequent des- 

 ignation of Fowler 1936). 



Diagnosis and description same as for family. 



Key to Species Based on Females 



The following key will differentiate female specimens >20 mm SL (for males and larvae see Bertelsen 

 1951). The key should be used in conjunction with Figures 19-24. 



lA. 



IB. 

 2A. 



2B. 



3A. 



3B. 



4A. 



Escal bulb width 11.3% SL in 111 mm specimen (Figures 18, 28); longest lower jaw tooth 

 5.9% SL in 111 mm specimen Melanocetus eustalus n. sp. (single known female) 



Escal bulb width <10% SL (Figure 17); longest lower jaw tooth 6.9-25.0% SL 2 



Anterior margin of vomer deeply concave (Figure 2); least outside width between frontals 

 9.1-17.8% SL (Figure 19); number of lower jaw teeth 46-142 (>60 in specimens 25 mm 

 and larger) (Figure 20); escal bulb width 1.9-5.1% SL (<3% SL in specimens >50 mm 

 SL) Melanocetus murrayi Giinther 1887 



Anterior margin of vomer nearly straight (Figure 1); least outside width between frontals 

 13.5-28.6% SL (Figure 19); number of lower jaw teeth 32-90 (Figure 20); escal bulb width 

 3.8-8.6% SL (>4% SL in specimens >50 mm SL) 3 



Longest lower jaw tooth 8.4-25.0% SL (Figure 21); esca with compressed posterior and 



(usually) anterior crests (Figure 25); distribution nearly cosmopolitan 



Melanocetus johnsoni Giinther 1864 



Longest lower jaw tooth 6.9-13.1% SL (Figure 21); esca without posterior or anterior crests 



(Figures 26, 27); distribution restricted to eastern tropical Pacific 4 



Number of lower jaw teeth 58-90 (Figure 22); escal bulb width 5.2-8.5% SL (Figure 23); 

 illicium length 34.6-56.0% SL (Figure 24); escal bulb with a conical, distal prolongation 

 occasionally pigmented on tip (Figure 26) Melanocetus polyactis Regan 1925 



70 



